1. Field of the Invention
The invention relates generally to an imbibition process for the uptake of water or other substances along with dissolved substances into a seed, more specifically, to a method of treating seeds with sound waves for the purpose of improving the rate of water and/or substance uptake into the seed wherein the substance enhances a growth characteristic of the seed or added value of the seed during commercial processing.
2. Background of the Prior Art
Seed dormancy is a unique form of developmental arrest utilized by most plants to temporally disperse germination and optimize progeny survival. During seed dormancy, moisture content and respiration rate are dramatically lowered. The initial step to break seed dormancy is the uptake of water (imbibition) necessary for respiration and mobilization of starch reserves required for germination. Imbibition is a biphasic process: 1) the physical uptake of water through the seed coat and hydration of the embryo and 2) germination as determined by growth and elongation of the embryonic axis resulting in emergence of the plumule and radicle. The two phases are separated temporally and seed which has completed phase I is said to be "primed seed," that is, primed for phase II: germination. Phase I of imbibition is also used in the commercial processing of seed, i.e. wet milling fractionation of corn and the malting process for the fermentation of distilled spirits.
Priming of seed by the enhanced imbibing of water is advantageous to plant vigor, e.g. enhanced emergence, growth and yield characteristics. Seed priming also synchronizes the germination of seed resulting in an uniform field of plants that matures simultaneously for maximal yields at harvest. In addition to water, seed priming provides access to load the seed with nutrients, microorganisms or pest inhibitors to promote seedling establishment. By adding the molecule to the seed during imbibition phase I, the molecule or organism can be stored in the primed seed and therefore, be present at planting. The "loading of macromolecules" is very efficient in the seed when compared to the addition of similar molecules to the entire field. An example is the addition of fertilizer to stimulate root growth and hasten seedling emergence. The loading of the fertilizer into the seed prior to planting is more efficacious to the seedling and cost effective to the farmer. Other beneficial molecules to be loaded into seed are hormones such as the gibberelins/gibberellic acid to promote germination, cytokinins for cell elongation and inhibitors of abscisic acid to promote release from seed dormancy. Seed cultivars could be customized to specific growing regions by the addition of triazoles (plant growth regulators which moderate the effects of drought and high temperatures) or fungicides to inhibit the growth of fungi on seed and seedlings in cool, wet soil or insecticides to combat insects that attack seedlings such as corn rootworm. In addition to macromolecules, beneficial microorganisms such as Azospirillum or Rhizobium can be loaded during seed priming as a crop innoculant.
The commercial fractionation of corn begins with wet milling. Corn is a complex mixture of starch, protein, oil, water, fiber, minerals, vitamins and pigments. Wet milling is the process of separating the corn components into separate, homogenous fractions. In Iowa, approximately 20% of the 1 billion bushels of corn harvested each year is wet milled. The wet milling industry and collateral manufacturers represent a prodigious industrial effort. As the wet milling process is constantly refined by new technologies, novel by-products can be isolated in industrial quantities, e.g. ethanol, corn sweeteners, protein peptides and vitamins C and E. The initial step in wet-milling, steeping, has not been altered by technological innovation. Steeping involves soaking the clean and dried corn (&lt;16% water content) in warm water until it has swollen to 45% hydration. This process takes from 30-50 hr. at temperatures of 120-130.degree. F. During the steeping process, large quantities of water are moved through massive vats of corn in a countercurrent stream. Also during this time, beneficial microorganisms such as the lactobacteria and Pseudomonas aeruginosa growing in the steep water aid in the proteolytic cleavage of corn proteins. However, the large volumes of steep water and the time required for hydration limit the effectiveness of the bacterial digestion. The digestion by-products are purified from the steep water primarily by evaporative concentration.
The malting process is the first step in the fermentation of grain to produce alcoholic spirits. The quality of the malt (and the resulting fermentation) is dependent upon the synchronous and efficient germination of the grain. Starches stored in the seed are converted into sugars during early stages of germination. At emergence, germination is halted and converted sugars are used during fermentation for the production of ethanol. Historically, the malting process was a labor intensive task. The grain was spread onto a malting floor, imbibed with water from overhead sprinklers, and turned by hand daily over the course of one to two weeks to release trapped heat and gases. At plumule emergence, the starches have been converted to sugars, the germinated grain is kiln dried and ground to form malt. Microbreweries and distilleries still use variations of this old malting technique to produce high quality malt. Some distilleries induce uniform germination by the addition of gibberllic acid (GA) to produce the highest quality of malt for fermentation such as in single malt scotch distillation. GA is the plant hormone which regulates germination. Malt production of this quality is time consuming and expensive.